德国波恩大学附属医院Florian Mormann和德国亚琛工业大学Marc Spehr课题组合作的研究，揭示了人大脑对气味的单神经元表征。2024年10月9日出版的《自然》杂志发表了这项成果。

据介绍，嗅觉是指导动物和人类行为的基本感觉模式。然而，人们对人类嗅觉的基本神经过程（即单神经元水平）仍然知之甚少。

研究人员记录了清醒个体在进行气味评级和识别任务时，梨状皮层和颞叶内侧单神经元的活动。研究人员在梨状皮层、杏仁核、内侧皮层和海马中发现了气味调制神经元。在这些区域中，神经元的发射都能准确地编码气味特征。值得注意的是，重复出现的气味会降低反应发射率，这表明中枢会发生重复抑制和习惯化。

不同的内侧颞叶区域在气味处理中发挥着不同的作用，杏仁核神经元编码主观气味识别，海马神经元预测行为气味识别性能。杏仁核神经元主要编码化学气味特征，而海马神经元的活动则反映了对主观气味的感知。重要的是，研究人员发现梨状皮层神经元能可靠地编码与气味相关的图像，这证明人梨状皮层发挥多模态作用。研究还观察到气味和图像的明显跨模态编码，尤其是在杏仁核和梨状皮层。

此外，研究还发现了对语义一致气味和图像信息做出反应的神经元，揭示了嗅觉中的概念编码方案。该研究结果弥合了动物模型和非侵入性人体研究之间长期存在的隔阂，并通过确定神经元气味编码原理、区域功能差异和跨模态整合，推进了人们对人脑气味处理的理解。

附：英文原文

Title: Single-neuron representations of odours in the human brain

Author: Kehl, Marcel S., Mackay, Sina, Ohla, Kathrin, Schneider, Matthias, Borger, Valeri, Surges, Rainer, Spehr, Marc, Mormann, Florian

Issue&Volume: 2024-10-09

Abstract: Olfaction is a fundamental sensory modality that guides animal and human behaviour1,2. However, the underlying neural processes of human olfaction are still poorly understood at the fundamental—that is, the single-neuron—level. Here we report recordings of single-neuron activity in the piriform cortex and medial temporal lobe in awake humans performing an odour rating and identification task. We identified odour-modulated neurons within the piriform cortex, amygdala, entorhinal cortex and hippocampus. In each of these regions, neuronal firing accurately encodes odour identity. Notably, repeated odour presentations reduce response firing rates, demonstrating central repetition suppression and habituation. Different medial temporal lobe regions have distinct roles in odour processing, with amygdala neurons encoding subjective odour valence, and hippocampal neurons predicting behavioural odour identification performance. Whereas piriform neurons preferably encode chemical odour identity, hippocampal activity reflects subjective odour perception. Critically, we identify that piriform cortex neurons reliably encode odour-related images, supporting a multimodal role of the human piriform cortex. We also observe marked cross-modal coding of both odours and images, especially in the amygdala and piriform cortex. Moreover, we identify neurons that respond to semantically coherent odour and image information, demonstrating conceptual coding schemes in olfaction. Our results bridge the long-standing gap between animal models and non-invasive human studies and advance our understanding of odour processing in the human brain by identifying neuronal odour-coding principles, regional functional differences and cross-modal integration.

DOI: 10.1038/s41586-024-08016-5

Source: https://www.nature.com/articles/s41586-024-08016-5